Search iTunes for the songs you want, and scroll through to see if the karaoke version of it pops up. Otherwise, search iTunes for karaoke songs in general, and scroll through the songs available.
Purchase the karaoke songs you want; they will download onto your computer.
Go to your iTunes account and select the music you wish to burn onto a CD.
Put a blank CD in the CD drive.
Select "File" in the left-hand corner, then select "Burn CD."
Install software that allows you to burn the song and the lyrics (see Resources) if you'd like to have both on the CD.
Purchase a drive that allows you to burn CD+Gs or DVDs if your computer didn't come with one.
Follow the step-by-step instructions provided by the software.